Gross reproduction rate

This article describes an attempt to use behavior of multiple birth cohorts in a single period and extrapolate from that to consider the outcomes for a hypothetical individual, who, at each age, behaves like the birth cohort for that age.

Definition

The gross reproduction rate (GRR) of a population based on measurements in a given year is defined as follows. It is the total number of daughters a female would have if she went through her childbearing years conforming to the age-specific fertility rate of that year, and assuming that she conforms to the sex ratio at birth for the population.

If we use a single (rather than age-specific) sex ratio at birth) then we can write:

Gross reproduction rate = (Total fertility rate) * ((100)/(100 + sex ratio at birth))

If we use age-specific sex ratios at birth, then we need to compute the age-specific reproduction rate as

age-specific reproduction rate = (age-specific fertility rate) * (100)/(100 + age-specific sex ratio at birth))

We then compute the gross reproduction rate by adding up the age-specific reproduction rates.